The present invention relates, in general, to assessing the operating conditions of one or more electromechanical machines, such as electric motors and, in particular, to the use of steady-state measurements of aggregate operating voltage and current signals, supplied to and/or from such machines, relative to known changes in steady-state conditions of one or more individual machines, to determine the discrete effect, to the aggregate signal, of such one or more individual machines and, to associate such discrete effect to the operating performance of such individual machine or machines. Optionally, a component of the assessment may include comparing such discrete effect with previous measurements of the same or similar machines to determine what level, if any, of deterioration in performance.
Many devices identified and tracked in industrial processes are critical to an ongoing production line, which if stopped for unplanned reasons, can result in substantial monetary loss to the owners and operators of such processes. Failure of such devices is usually progressive and can happen over the course of months and years. Examples of such devices include refrigerators, air conditioners, pumps, motors, generators, compressors, and fans. Many times, the operating characteristics of these devices is unknown and/or the ongoing operation of these devices is taken for granted and, unfortunately, the devices are usually not serviced until they fail.
Existing industry methods for identifying the operating performance of a given electromechanical machine or driver device consist of either 1) connecting one or more sensors to each individual machine or device and measuring the sensor outputs directly to determine operating performance, or 2) measuring the aggregate voltage and current signals associated with multiple machines and devices, all connected to a common electrical supply network, and performing analysis based on predetermined time-dependent behaviors of each individual machine or device. An example of such a time-dependent behavior would be a turn-on event.
Methods which assess machine performance utilizing measurements taken from individual sensors connected to each individual machine in a network, require significant physical infrastructure and/or financial investment associated with installing sensors on each of multiple machines and running wiring from each machine to one or more intelligent devices to analyze and process the measured signals.
Methods which assess machine performance without the need for sensors connected to each individual machine, but instead make aggregate measurements of voltage and current signals traveling to/from multiple machines on a commonly supplied electrical network, require the use of predetermined time-dependent behaviors of the individual machines, such as turn-on events, possess significant shortcomings in that performance related problems typically associated with time-dependent events, such as turn-on events, are typically caused by machine-connected driver devices and not the machines themselves. Thus, in many cases, such methods fail to notice certain operating performance problems associated with the critical and expensive machine, but instead may only notice performance problems associated with the less critical and inexpensive driver device which may be connected to such critical machine. Examples of such inexpensive driver devices include a motor start capacitor, which typically runs for 0.1 to 1 second in time while starting. As another example, many critical machines such as air conditioners are generally turned on and off by a mechanical relay device. Such relays typically fail because the contacts erode due to arcing. The arcing generally occurs only during startup, so the load may continue to start until a contact completely fails.